1. Field of the Invention
The present invention relates to a portable GPS signal receiving device used in leisure or sports activities. In particular, the present invention relates to a portable GPS velocity/distance meter performing a velocity measuring method of a moving object by utilizing a Doppler frequency of a carrier wave of GPS waves and a velocity measuring method for calculating a movement velocity from time information and a difference in positional information within obtained measured data by conducting measurement several times.
2. Description of the Related Art
A GPS system which is a satellite navigation system in which a continuous three-dimensional positional measurement is possible from any place on the earth and, at the same time, a velocity and an advancing orientation of a moving object may be obtained independently is applied to a car navigation system which has, recently, rapidly been used and accommodated. Also, in leisure or sports activities, a GPS signal receiving device is miniaturized so that it has been extensively used as a simplified portable positioning device.
For instance, Japanese Patent Application Laid-Open No. Hei 4-351981 discloses a conventional portable GPS signal receiving device. This portable GPS signal receiving device is a GPS signal receiving device with a GPS signal receiving function for calculating positional information including latitude, longitude and altitude at a current time and further calculating an orientation and a distance to represent them on a display device. This is characterized in that an electric power is provided by a solar battery provided on a cover of the signal receiving device body.
Also, Japanese Patent Application Laid-Open No. Hei 6-118156 discloses a portable GPS signal receiving device, in a palm-top size, which is composed of a signal receiving section for receiving a GPS signal from a GPS satellite, a positional information calculating section for calculating positional information for every predetermined period of time from the GPS signal during movement of the moving object, a memory section for storing positional information for every predetermined period of time, a movement situation calculation section for calculating a moving distance for every predetermined period of time and total movement distance on the basis of the positional information for every predetermined period of time stored in this memory section, and a display section for displaying the movement situation that is the information as a result of the calculation.
Furthermore, Japanese Patent Application Laid-Open No. Hei 9-145814 discloses a card size portable GPS signal receiving device, i.e., a so-called portable car navigation system signal receiving device, in which a liquid crystal display and various operation keys are provided on an outer surface of a card type case and a map memory card (ROM) is detachably inserted into the card type case. In the interior of the card type case, there are provided a patch type antenna for receiving a GPS signal from a GPS satellite, a GPS signal receiving section for obtaining positional data of the moving object by processing the received GPS signal, a calculation processing section for calculating the current position of the moving object on the bases of the obtained positional data and a display controlling section for superimposing the current position of the calculated moving object on the map read out from the map memory card to display it on the liquid crystal display screen.
variety of equipment used in leisure or a sports activities is generally required to be superior in portability and operability. Any conventional device described above would meet these requirements to some extent but it is hard to say that such a device satisfactorily meets the requirements. Therefore, a wristwatch type GPS signal receiving device that is particularly superior in portability has been demanded. For the wristwatch type device, it is impossible to realize a portable car navigation system signal receiving device provided with the map memory card as disclosed in Japanese Patent Application Laid-Open No. Hei 9-145814 due to the size of the map memory card. Accordingly, the compact portable GPS signal receiving device like the wristwatch type devise is basically used as the velocity/distance meter for displaying the time, velocity, distance or the like by numbers on the liquid crystal display section.
There are two methods for determining the movement distance from a point A to a point B and the movement velocity by utilizing the positional data from the GPS signal receiving device. First of all, there is a first method in which the latitude and the longitude of the points A and B are measured respectively, the distance between the points is taken as the movement distance, and this movement distance is divided by the known movement time to obtain the movement velocity. However, this method is only applicable to the basic case where the moving object moves linearly. In the case where the moving object does not move linearly, as described in Japanese Patent Application Laid-Open No. Hei 6-118156, it is necessary to conduct the measurement by dividing the path in a number of linear portions. In addition, the GPS service that is now available is a so-called SPS in which a C/A code and a navigation message are only used for positioning. Since the measurement width of the absolute position is in the range of 10 to 100 m in radius, the measurement accuracy is not very high. Accordingly, velocity measurement method for a moving object is done utilizing a method using the Doppler frequency of a carrier wave of the GPS waves. This is a velocity measurement method which utilizes the fact that the Doppler frequency is in proportion to the movement velocity if the carrier wave has a constant value. According to this measurement method, since the movement velocity of the moving object may be instantaneously measured by measuring the Doppler frequency, it is possible to apply this system to a meandering road or a circuit course of a track.
According to the portable GPS velocity/distance meter of the present invention, there is adopted a velocity measurement method for the moving object by utilizing the Doppler frequency of the carrier wave of the GPS waves or a velocity measurement method for conducting positional measurement a plurality of times and calculating the movement velocity from the time information and difference is positional information within the obtained positional data. Also, both the velocity measurement methods may be used in combination. However, a human being walks or runs while waving his arms back and forth toward and away from the advancing direction. In the static condition, since the velocity of the arms waving up and down is zero when the conversion from the swing-up to the swing-down of the arms and at maximum when the arms pass through the lowest point. During this period, the velocity is gradually changed. Accordingly, the sine curve is depicted if the lateral axis represents time. On the other hand, the velocity of the advancing direction of the body is not periodically changed but may be kept substantially constant relative to the time axis. Since the wristwatch type GPS velocity/distance meter is attached to the wrist, the velocity relative to the ground is a composition of the moving velocity of the body and the velocity of the swing-up and swing-down of the arm. Accordingly, the velocity measured by the wristwatch type GPS velocity/distance meter is the composition velocity and is not the movement velocity of the human being, i.e., a carrier. For this reason, in the portable GPS velocity/distance meter, since there is an effect of the swing-up and swing-down of the arm, there is a problem in that it is impossible to obtain a desired movement velocity for the intended purpose. Also, not only the waving up and down of the arm but also the periodical up-and-down movement of the body in walking or running would interfere with the desired movement velocity.
Also, in the portable GPS velocity/distance meter, and in particular, the wristwatch type GPS velocity/distance meter, due to the size of the overall device, it is inevitable to use a small-size battery. However, GPS signal receiving device consumes a rather large power during the operation. This is a very large load for the small-size battery.
Furthermore, in case of training of a marathon runner or training of a long-distance runner, a coach has to always understand the running condition or the like and to give a suitable instruction such as change in pitch or the like. In training for track, events it is possible to know the running condition of the runner on the basis of the lap time for every turn. However, in the training in a general road, it is not easy for the coach to follow the runner on a ride in an automotive vehicle or a bicycle. He could not know the running condition of the runner appropriately. Accordingly, it is necessary to realize a portable GPS velocity/distance meter by which it is possible to monitor, from a distant point, the data of the running conditions such as a running velocity, a running pitch, a lap time or the like of the long-distance runner during training, and to give the runner appropriate instructions at an appropriate timing.
A first object of the present invention is to provide a portable GPS velocity/distance meter utilizing a GPS signal to seek a suitable movement velocity of a carrier while removing an adverse effect of a periodic movement such as up-and-down movement of a body or up-and-down swing motion of an arm which occurs when the carrier walks or runs.
A second object of the present invention is to provide a portable GPS velocity/distance meter utilizing a GPS wave to reduce power consumption of the device to make it possible to prolong the use for an extended period of time.
A third object of the present invention is to provide a portable GPS velocity/distance meter by which not only the carrier but also a person at a remote position may know movement conditions such as movement velocity, distance or the like of the carrier.
A fourth object of the present invention is to provide a portable GPS velocity/distance meter utilizing a GPS signal to minimize an error in movement velocity and movement distance calculated, while suppressing the adverse affect of SA (selective availability).
In order to solve the first, second and fourth objects, according to the present invention, there is provided a portable GPS velocity/distance meter comprising: a GPS signal receiving section for receiving a signal from a GPS satellite and outputting positional data including movement velocity of a moving object; a microcomputer for performing various controls and calculations in accordance with a program; and input section for setting a condition of the various controls and calculations including the operational timing of the positional operation of the GPS signal receiving section in the microcomputer; and a display section for displaying movement velocity and movement distance of the carrier that is the moving object under the control of the microcomputer, and further comprising: a control means for controlling the GPS signal receiving section on the basis of the operational timing to intermittently perform the positional operation at predetermined intervals; and a velocity averaging means for averaging the movement velocity.
In order to solve the first, third and fourth objects, according to the present invention, there is provided a portable GPS velocity/distance meter comprising: a GPS signal receiving section for receiving a signal from a GPS satellite and outputting positional data including movement velocity of a moving object; a microcomputer for performing various controls and calculations in accordance with a program; and input section for setting a condition of the various controls and calculations including positional interval data of the GPS signal receiving section in the microcomputer; a display section for displaying movement velocity and movement distance of the carrier that is the moving object under the control of the microcomputer; and a transmit-receive section for connecting a remote supervising device and the microcomputer with each other in a wireless manner, and further comprising: a control means for controlling the GPS signal receiving section on the basis of the positional interval to intermittently perform the positional operation; and a velocity averaging means for averaging the movement velocity wherein the transmit-receive section further comprises a means for transmitting the data such as a velocity and a distance calculated by the microcomputer to the remote supervising device. The transmit-receive section further comprises a means for receiving a change command signal of various calculation control conditions from the remote supervising device and the microcomputer has a means for performing setting and changing the various calculation control conditions in accordance with the change command signal.